Monte Carlo simulations of the structure of magnetic fluid composites

Monte Carlo simulations have been used to determine the structure of thin film composites containing polystyrene spheres 1 mu m in diameter dispersed in a 50 kA m -1 magnetic fluid. The aggregate structures observed in a magnetic field of 2 mT correspond closely to those which are observed experimentally for both high (16%) and low (6%) concentrations of spheres. The analysis predicts a variation in structure with magnetic field orientation, giving a change from a regular hexagonal lattice structure when the field is perpendicular to the plane of the film to a system of chain aggregates when the field is at an angle of approximately=60 degrees to the plane of the film.